The present invention relates to a magnetic recorder and regenerator having, in its recorder system, a luminance signal input terminal for receiving a luminance signal and a line-sequential signal input terminal for receiving a line-sequential signal consisting of a series of alternately line-sequenced color differential signals having a d.c. level difference therebetween, the line-sequential signal and the luminance signal being frequency-modulated and recorded in a magnetic recording medium. The present invention relates in particular to a magnetic recorder and regenerator of the above-described type which is capable of dubbing signal without incurring any picture quality deterioration.
A magnetic recorder and regenerator, such as an electronic still camera, is known which comprises a recorder system and a regenerator system. The recorder system is adapted to frequency-modulate a line-sequential signal from a line-sequencing circuit which produces the line-sequential signal by alternately line-sequencing color differential signals while frequency-modulating a luminance signal, and is further adapted to synthesize a recording signal by frequency-superposing the thus frequency-modulated line-sequential and luminance signals, the recording signal being recorded on a magnetic recording medium. The regenerator system is adapted to reproduce the luminance and line-sequential signals by frequency-demodulating the signals recorded on the magnetic recording medium, and to regenerate the original color differential signals by rearranging the line-sequential signal into the original parallel color differential signals by means of a rearranging circuit. See Japanese laid-open patent application 206397/1985, for example.
As shown in FIG. 1, dubbing may be done using two magnetic recorder and regenerators 1, 2. By dubbing, recordings on a magnetic recording medium set in one magnetic recorder and regenerator 1 are recorded on the other magnetic recorder and regenerator 2.
Prior art apparatus 1, 2 have connection terminals which include a luminance signal input terminal 4 and color differential signal input terminals 5, 6 provided on the input side of the recorder system 3, and a luminance signal output terminal 8 and color differential signal output terminals 9, 10 provided on the output side of the regenerator system 7. For the dubbing operation, the luminance signal output terminal 8 of apparatus 1 is connected to the luminance signal input terminal 4 of apparatus 2, while the color differential signal output terminals 9, 10 of apparatus 1 are connected to the color differential signal input terminals 5, 6 of apparatus 2, respectively.
In the dubbing process by the prior art magnetic recorder and regenerator apparatus 1, 2, color differential signals reproduced by the rearranging circuit in the regenerator system 7 of apparatus 1, are again line-sequenced by the line-sequencing circuit in the recorder system 3 of apparatus 2 and then recorded on a magnetic recording medium set in apparatus 2.
The rearranging of color differential signals by the rearranging circuit in the regenerator system 7 of apparatus 1, as well as the line-sequencing of these color differential signals by the line-sequencing circuit in recorder system 3 of apparatus 2, however, is essentially not necessary in the dubbing process because the color differential signals are recorded on a recording medium in the line-sequenced form. A dubbing process by means of such prior art apparatus, involving the essentially unnecessary steps of the rearranging and the subsequent line-sequencing of color differential signals, is therefore accompanied by a deterioration in of picture quality due to such unnecessary steps.
Thus, an arrangement has been proposed which comprises a line-sequential signal output terminal for extracting the frequency-demodulated line-sequential signal during the dubbing process, which terminal is provided on the input side of the rearranging circuit in the reproducer system, and a line-sequential signal input terminal provided on the output side of the line-sequencing circuit in the recorder system, which terminal is switched for receiving the line-sequential signal from the line-sequential signal output terminal during the dubbing process. When signals recorded on a magnetic recording medium set in one magnetic recorder and regenerator are to be dubbed onto another magnetic recording medium set in another magnetic recorder and regenerator, the line-sequential signal may be transferred, before being supplied to the rearranging circuit, from one magnetic recorder and regenerator to the output side of the line-sequencing circuit in the recorder system of the other magnetic recorder and regenerator, whereby the signals may be dubbed onto the magnetic medium set in the other recorder and regenerator.
The above-described arrangement does not require the essentially unnecessary steps of rearranging and line-sequencing color differential signals during the dubbing process, and therefore, will not suffer from a picture quantity deterioration which can otherwise arise from such steps.
Picture quality deterioration may occur from factors other than the above-described steps. For example, it may occur if a luminance or line-sequential signal with fluctuation in the level thereof is supplied for recording, without any compensating process, from the regenerator system of a magnetic recorder and regenerator to the recorder system of another magnetic recorder and regenerator. Such fluctuation, however, will cause deterioration in the picture quality in the dubbing process and will make it difficult to accurately reproduce color pictures.
Further, in electronic still cameras, an R-Y component color differential signal, or red color differential signal, and a B-Y component color differential signal, or blue color differential signal, are used which have different d.c. levels V.sub.1 and V.sub.2 (see FIG. 2). The d.c. level difference is provided between these R-Y and B-Y color differential signals in order to give them different center frequencies f.sub.1 and f.sub.2 by means of frequency-modulation, such difference between the center frequencies being essential to the separation of such R-Y and B-Y components in the step of regenerating the line-sequential signal. These center frequencies f.sub.1 and f.sub.2 are set to 1.2 MHz and 1.3 MHz, respectively.
Thus, if the line-sequential signal fluctuates in the d.c. levels V.sub.1 and V.sub.2, the center frequencies f.sub.1 and f.sub.2 fluctuate in response to the fluctuation of the line-sequential signal, and a deterioration of the picture quality is caused. Thus, the d.c. levels V.sub.1 and V.sub.2 must be kept constant by clampers.
In such a case, since the reference d.c. levels V.sub.1 and V.sub.2 will alternate with each other upon the termination of each horizontal scanning cycle, it is conceivable that a signal with a frequency equal to one half of the horizontal scanning frequency may be used as the clamp timing a signal. Such signal with the frequency equal to one half of that of the horizontal scanning frequency, however, will in itself not determine whether the clamped d.c. level is the R-Y component d.c. level V.sub.1 or the B-Y component d.c. level V.sub.2. If a timing error in the d.c. levels occur, the line-sequential signal will include errors, due to the erroneous clamp timing which will be recorded, causing further deteriorations in the picture quality. Prior art magnetic recorder and regenerators will not be able to faithfully reproduce such color pictures.